Relationship of Changes in Spherical Aberration and K Values of Cornea After Cataract Surgery
Purpose
It has been observed in our previous studies that there is significant change in spherical aberration of cornea and K values after cataract surgery. The purpose is to find out is there any relationship.
Methods
239 eyes having cataract patients were evaluated on corneal topographer. Mean K values in central (0 to 3 mm D), mid (3 mm to 6 mm D) and peripheral zone (6 mm to 9 mm D) and spherical aberration were recorded pre op. and 1 month post op. 2 corneal stab incisions of 0.9 mm at 2.30 and 9.30 o’clock at limbus were made. Main phaco wound of 1.8 mm size was made at 11 o’clock and was enlarged to 2.4 mm (Group A), 2.8 mm (Group B) or 5.4 mm (Group C) depending up on the size of IOL implanted.
Results
There were interesting observations. In Group A (2.4 mm phaco wound), where there was increase in SA (36.47%), central cornea (0 to 3 mm area) became flat by 0.27% whereas, where SA decreased by 20.88%, central area became steep by 0.11%. in Group B (2.8 mm phaco wound), central cornea became flat by 0.87% whereas SA increased by 36.45%, while it became steep by 0.26% where SA decreased by 20.88%. Similarly in Group C (wound size 5.4 mm), central cornea became flat but by only 0.06% (sclerocorneal wound) while it became steep by 0.45% where SA was found decreased by 26.57%.
Conclusion
Central cornea i.e. 0 to 3 mm area was affected maximum. It became flat where SA increased while it became steep where SA was decreased. This relationship can play a major role in understanding of changes so that an IOL with appropriate SA can be selected for better ocular asphericity.